During his appearance on The Late Show on Monday, host David Letterman asked Sheen, "You are going to be, in the next several months... fill in the blanks.""Grandfather," Sheen happily replied. The actor explained that oldest daughter Cassandra Estevez, 28, is pregnant with her first child with husband Casey Huffman.Sheen, who suffered a very public meltdown in 2011, joked that he'd definitely be a good grandfather "because you can leave the kid!"

Though Estevez's mother is Sheen's high school girlfriend Paula Profit, the actor's second ex-wife shared in Sheen's joy. "I guess some of you have heard... Charlie Sheen is going to be a Grampa... yes GRAMPA! His beautiful daughter Cassandra is gonna be a mama," Denise Richardstweeted.While Sheen said the news is "fabulous," he admitted that he's not quite "ready to adopt" the title just yet. Maybe he can take a cue from Real Housewives' NeNe Leakes and be the world's first glamfather?Watch a sneak peek of Sheen's Wednesday appearance on Oz.